Rotary drum evaporator with concentric evaporating chambers



Jan. 3, 1950 J. E. BIBBY ROTARY DRUM EVAPORATOR WITH CONCENTRICEVAPORATING CHAMBERS 4 Sheets-Sheet 1 Filed Aug. 15, 1946 m I. n e U n IA ltorney Jan. 3, 1950 J. E. BIBBY 2,493,220

ROTARY DRUM EVAPORATOR WITH CONCENTRIC EVAPORATING CHAMBERS Filed Aug.15, 1946 4 Sheets-Sheet 2 F/GZ. l4 /7 Inuenlor Z Z By Attorney Jan. 3,1950 J. E. BIBBY 2,493,220

ROTARY DRUM EVAPORATOR WITH CONCENTRIC EVAPORATING CHAMBERS Filed Aug.15, 1946 4 Sheets-Sheet 3 A ltorney Jan. 3, 1950 J. E. BIBBY ROTARY DRUMEVAPORATOR WITH CONCENTRIC EVAPORAT ING CHAMBER 4 Sheets-Sheet 4 FiledAug. 15, 1946 F/GS Invenlor Bz6&y y

\ A llorney Patented Jan. 3, 1950 UNITED STATES, PATENT OFFICE ROTARYDRUM EVAPOBATOB GON- CENTBIC EVAPOBATING CHAMBERS James Edward Bibby,Birkenhead, England, '18- signor to J. Bibby & Sons Limited, LiverpooEngland, a British company Application August 15, 1946, Serial No.890,784 In Great Britain September 6,1945

'1 claim. (Cl. 202-236) liquids having a tendency to foam or frothduring evaporation, or liquids containing small quantities of finelydivide'd solids.

A highly successful application of the invention is to a machine for thetreatment of .oil which has been extracted by means of solvents, themachine being used after the extraction process has been completed toseparate and recover" the solvents from the oil. A further applicationof. the invention is to a machine for the deodorization and liketreatment of oils, e. g. palm oil, cotton seed oil, soya bean oil andthe like.

According to the present invention there is provided an evaporatorcomprising a casing having a heating jacket, a drum or like member insaid casing and having its. peripheral surface spaced from the interiorof the casing to form an evaporation chamber, either or both the easingand the drum being relatively rotatable, inlet means for introducingliquid to be treated (e. g. 011 and solvent) into'said evaporationchamber and an outlet for the evaporate (e. g. solvent).

In the preferred embodiment of the invention the casing is stationaryand the drum is rotated.

'Due to the rotation of the drum, onto the surface of which the mixtureof oil and solvent is fed, centrifugal force acts to maintain a skin orfilm of the liquid on the interior face of the casing or heating jacketso that said film is rapidly heated and the solvent evaporated.Preferably there are blades in the evaporation chamber which servecontinuously to change the surface of the liquid in contact with theheating surface. Thisresults in a rapid and highly ellicient transfer ofheat from the heating Jacket to the liquid. The film of liquid may betraversed along the length of the casing, in contact with the heatingjacket, by a series of angularly disposed plates or blades which work inthe evaporation chamber. Conveniently some, at least, of the blades arearranged to scrape the interior face of the casing.

To provide a second-stage" evaporator, the interior of the rotatabledrum-like member may be divided by radially spaced circumferentialpartitions into a plurality of annular chambers.

The innermost chamber has an inlet for steam or other gaseous media(hereinafter referred to as steam) and an outlet for residual liquid andtheoutermost chamber has an inlet for the liquid to be treated further(say, oil and solvent) and an outlet for the steam, or vice transfers itto the next chamber.

versa. Transfer means are provided in the partitions for the transfer ofoil and solvent'from one chamber to the next, said transfer meansincluding a scoop-like member which receives. or gathers, the oil andsolvent, from the body of cascading oil and solvent built up at one sideof each chamber due to the rotation thereof, and This process oftransfer continues from annular chamber to annular chamber'until the oiland solvent have. passed from the outermost chamber to the inner mostchamber (or vice versa) via a very long path and in contact with and, atleast in part, counter-current to the steam. Due to this long path offlow in the form of a rapidly moving cascade the steam evaporates andcarries of! with it the solvent in an eflicient and eflective manner andleaves the oil substantially, if not completely, free of solvent.Preferably the trans-'- fer of oil and solvent from one annular chamberto another takesplace alternately at opposite ends of the chambers so asfurther to increase the distance the oil and solvent have to flowcounter-current to the steam.

Preferably each of the aforementioned partltions comprises at least twoand preferably more arcuate elements or plates spaced apart or staggeredradially to form apertures or passages in said partitions for thetransfer of steam and evaporated solvent from one chamber to the nextvia a sinuous path and counter-current, at least in part, to the oil andsolvent. The combination of aprimary evaporator having a steam jacketand rotating drum-like mem-'- ber, forming an evaporating chamber, and asec-.-

ondary evaporator comprising a series of annular chambers as justdescribed, provides a particu'- larly compact and efllcient machine.

One specific embodiment ,of the invention as applied to an evaporatorfor the evaporation and recovery of solvent from oil will now bedescribed by way of example with reference to the accompanying drawings,the figures of which are semi-diagrammatic in character- ,On thedrawings: L Figures 1 and 2 are complementary'views showing the machinein sectional elevation, the section being taken vertically through theaxis of the machine: I Figure 3 is a cross-section on the line 1II1I|Iof Figure 2;

Figure 4 is a fragmentary detail perspective view of a part of thescraper construction for the primary evaporator part of the machine, andFigure 5 is a fragmentary detail sectional view of the scoopconstruction which forms a part of the secondary evaporator part of themachine.-.- A

The machine comprises a cylindrical casing Ill closed at its ends by endplates Ii having can-.- trally-located bearings ii for supporting aroaaaaaao 3 tatable shaft It. A drum 2. is located within the casing itand is spaced from the interior thereof to form an annular evaporationchamber it.

steam or other heating jacket i'l (hereinafter called a steam packet)surrounds the casing, this steam jacket being provided with an inlet itfor steam and with the necessary drainage means it and the like. Thesteam jacket is lagged, as indicated at 20, to prevent loss of heat. Aninlet ii for the mixture of oil and solvent is provided at one end ofthe casing II and enters the aforementioned evaporation chamber ittangentially with respect to the drum-like member it, IS. Rows ofradially Pr jecting blades 2: are punched up out of the arcuate sectionsof the bladed structure II of the drum. There are also blades 24 or likemembers resiliently mounted on the armate sections II and pressed intocontact with the interior surface of the casing ll so as to scrape saidsurface. The blades 22 and It ensure changing of the liquid film on saidinterior surface continuously and this promotes rapid evaporation. Theblades 24 are inclined'with respect to the plane of rotation of the drumso that as the drum rotates the liqud is traversed along the evaporationchamber it towards the end 23 thereof 'remote from the inlet II for oiland solvent. It will be noted that the arcuate sections overhang theirsupporting brackets 2| as indicated at Ila to provide the requiredresilient support for the blades 24. The end of the evaporation chamberit, remote from the inlet II, is open as indicated at 28 and the oil andany remaining solvent therein pass from the primary or first-stage partof the machine via this opening into an annular cavity 20, between theend plates II and II, from which it iiows to the secondary evaporatorpart of the machine hereinafter described, by way of a transversecollecting tray "a, a spout 20b, and an opening lie in the right-handend plate ll. Solvent evaporated oil from the mixture of solvent and oilin the evaporation chamber it finds its way to, and passes from, themachine via an outlet duct it at the end thereof remote from that atwhich the oil is discharged.

The secondary evaporating part of the machine is housed within the drum2. and comprises a series of radially spaced circmnferential partitionsll secured at their ends in the end plates i4 and located concentricallyone within the other so as to divide the interior of the drum into aplurality of annular chambers I2.

Each of the annular partitions 3i comprises several arcuate-platesections, the ends or which overlap, the sections being displaced orstaggered radially with respect to one another so that where theyoverlap a passage-way a is formed for the flow of steam'and evaporatedliquid (e. g. solvent) from one chamber to the next. The axiallyextending edges 34 of the plates in the neighbourhood of said passagesare turned inwardly whilst bailles ll are located just ahead of the exitends of said passages so that steam flowing from the passages issues ina radial direction. The arcuate sections of each partition 3| aremaintained in their radially spaced relationship by spacing pieces 38.Each partition ll carries several radial projecting scoop-like members31 which open into the passage-ways it for the 4 transfer of oil andsolvent from one annular chamber 32 to the next. These scoop-likemembers are located alternately at opposite ends of the chambers.

The outermost of the annular chambers 32 communicates with the opening:lc by which the partially treated oil is discharged from the primaryevaporator part of the machine above described. The innermost of theannular chambers 32 communicates with an opening ll in the right-handplate II, which opening in turn communicates with a sump ll forreceiving the oil after final. treatment. the oil passing from the sump.via a port I, to a pump 42 by which it is discharged from the machine.An inlet It is provided for the injection of steam into the innermost ofthe chambers 82 via theport 80..

The operation of the machine above described is as follows:

The mixture of oil and solvent from whichthesolventistobeextractedandrecoveredisintroduced, via the inlet ii,into the primary evaporation chamber II and, due to the rotation of thedrum member ll. II and centrifugal force and the blades 22 and 24, iscaused to become a rapidly moving and changing illm on the interior faceof the casing ll 01 the steam jacket II. In its passage from one end ofthe evaporation chamber it to the other the liquid is heated and a part,at least, of the solvent is driven oil! andpassesfromthemachinetoacondenserviathe aforementioned vapour outlet 8|.The liquid oil passes from the primary evaporation chainber II to theoutermost of the annular chambers 32 of the secondary evaporator and,due to the rotation of the inner drum and partitions ll, builds up as ament-like body of cascading liquid to one side of the drum. When thisbody of liquid reaches a predetermined thickness some of it is gatheredby, or cascades into, the scoops 31 on the neighbouring partition and istransferred into the next annular chamber 82 where it again builds upinto a segment-like body of cascading liquid at one side of the chamber32.

.1hisliquidinturnisgatheredinthes'coopafl of the neighbouring. partitionand transferred to the next chamber II. This procedure is carried onright through the several annularchambersandinasmuchasthescoopsarearranged alternately at opposite endsor the drum the liquid flows sinuously through the several chambers fromthe outermost to the innermost. The manner in which the liquid builds upat one side of each chamber is indicated diagrammatically atLinFigureS.Whilstthisiiowofoilandsolvent is taking place in the one directionthrough the chambers 32, steam is flowing in the opposite directionthrough said chambers and is evaporating and taking up the remainingsolvent from an the oil and carrying it away via the aforementionedvapour outlet II. It is appropriate to mention that the open mouths ofthe scoops I1 and the steam outlets II from the chambers 32 lead withrespect to the direction of rotation as of the chambers. the directionof rotation being indicated by the arrow in Figure 3. The segmentshapedbody L of liquid at one side or each annular chamber 32 tends, ofcourse, to remain stationary relatively to the rotating structure 10once it has been built up to a height and thickof the liquid. The stageat which liquid is transferred from one annularchamber 32 to the nextdepends, of course, on the position of the scoops 31. i. e. the spacingof the scoops from the-neighbouring partition 3| from which they gatherthe liquid.

It is convenient, in order to facilitate assembly of the severalelements forming a partition 3!, to

secure such elements to the end plates of the drum by means of bolt-likedevices 44 which are slid into holes in the end plates l4 and aretrapped against being removed therefrom, as each succeeding partitionelement or plate is located in position.

In some cases the secondary evaporation part of the machine may bedispensed with, whereas in other cases the secondary part may comprise amachine separate from (i. e. not within) the primary part. A machine ofthis character forms the subject-matter of our co-pending applicationfor Patent No. 690,765 filed August 15, 1946 now Patent 2,484,445granted October 11, 1949.

A condenser and suction apparatus are generally connected to the machineas indicated diagrammatically at 45 and 46 respectively in Figure 1. Forcertain purposes (e. g. for the deodorization of oils) it is desirableto maintain a high degree of vacuum in the machine.

In some cases the passage-ways 33 may be closed entirely, or bedispensed with, in the neighbourhood of the spacing pieces 36. In suchan arrangement the steam flows counter-current to the oil by way of thescoops 31.

I claim:

1. An evaporator, comprising a casing, a cylindrical drum rotatablymounted in said casing with its axis of rotation horizontal and havingits peripheral surface spaced from the interior surface of the casing toprovide an evaporation chamber between said surfaces, aheating means forsaid chamber, inlet means for introducing liquid to be treated into saidevaporation chamber, an outlet for vapor, discharge means for residualliquid and blades on the drum working on the interior surface of thecasing, some at least of the blades extending in a slantwise directionaround and along the peripheral surface of the drum, spaced apartapertured circumferential partitions within the drum dividing it into aseries of annular cham-' bers, means connecting the evaporation chamberto the outermost annular chamber for the passage of residual liquidthereto, at least one scoop on each partition and in register with anaperture therein for scooping up liquid from a body of liquid thrown bycentrifugal force due to the speed of rotation of the drum against theouter peripheral surface of an annular chamber, saidv scoop transferringthe liquid inwardly to the next inner chamber as the drum rotates, meansfor passing steam through the annular chambers, an outlet for vapor andan outlet in the innermost chamber for residual liquid.

2. An evaporator, comprising a casing, a cylindrical drum rotatablymounted in said casing with its axis of rotation horizontal and havingits peripheral surface spaced from the interior surface of the casing toprovide an evaporation chamber between said surfaces, heating means forsaid surface of the casing, some at least of the blades extending in aslant-wise direction around and along the peripheral surfaceof the drumto cause the liquid to move along the evaporation chamber, spaced-apartapertured circumferential par titions within the drum concentricallyarranged and dividing the interior of the druminto several annularchambers, means connecting the evaporation chamber to the outermostannular chamber for the passage of residual liquid thereto, means .fordischarging the residual liquid from the inner? most annular chamber,-means for passing steam through each of the annular chambers in turncountercurrent to the liquid, an outlet means for vapor from the annularchambers and at least one scoop on each partition and in register withan aperture therein for scooping up liquid from a body of liquid thrownby centrifugal force due to the speed of rotation of the drum and lyingagainst the outer peripheral surface of an annular chamber andtransferring the liquid inwardly to-the next inner chamber as the drumrotates.

3. An evaporator, comprising a casing, a cylindrical drum rotatablymounted in said casing with its axis of rotation horizontal and havingits peripheral surface spaced from the interior surface of the casingto-provide an evaporation chamber between said surfaces, heatingmeansthe blades being arranged in several axially extending rows, theblades in One row being staggered with respect to the blades in aneighboring row, and other blades extending in a slant-wise chamber,inlet means for introducing liquid to I direction around and along theperipheral surface of the arcuate plates, spaced-apart aperturedpartitions within the drum concentrically arranged and dividing theinterior of the drum into several annular chambers, means connecting theresidual liquid discharge means in the evaporation chamber to theoutermost of the annular chambers, means for discharging the residualliquid from the innermost annular chamber, means for passing steamthrough each of the annular chambers in turn countercurrent to theliquid, an outlet means for the vapor from the annular chambers and atleast one scoop-on each partition and in register with an aperturetherein for scooping up liquid from a body of liquid thrown bycentrifugal force due to the speed of rotation of the drum against theouter peripheral surface of an annular chamber and transferring theliquid inwardly to the next inner chamber as tions spaced apart radiallyand overlapped at their ends to form the apertures for the flow of vaporfrom om. annular chamber to the next.

5, An evaporator as claimed in claim 2, wherein the partitions formingthe annular chambers each comprises several imperforate arcuate sectionsspaced apart radially and overlapped at their ends to form the aperturesfor the flow of vapor from one annular chamber to the next,

baflles being provided where one annular cham- 7. ber communicates withanother for the passage of vapor; V

6. An evaporator, comprising a casing, a cylindrical drum rotatabiymounted in said casing with its axis of rotation horizontal and havingits peripheral surface spaced from the interior surface of the casing toprovide an evaporation chamber between said surfaces, a heating meansfor said chamber, inlet means for introducing liquid to be treated intosaid evaporation chamber, an outlet for vapor, discharge means forresidual liquid, blades projecting outwardly from arcuate plates mountedon the drum concentrically therewith, some at least of the. arcuateplates having a resilient part which carries the scraper blades andmaintains them operative to scrape the interior surface of the casing,some of the blades being arranged in several axially ex tending rows,the blades in one row being staggered with respect to the blades in aneighboring row, other blades extending in a slant-wise direction aroundand along the peripheral surface of the arcuate plates to cause theliquid to move along the evaporation chamber from the liquid inlet meansto the residual liquid discharge means, the latter being displaced alongthe chamber with regard to said liquid inlet means, spacedapartpartitions comprising several imperforate arcuate sections spaced apartradially and overlapped at their ends, said partitions beingconcentrically arranged and dividing the interior of the drum intoseveral annular chambers and providing apertures for the flow of vaporfrom one annular chamber to the next, means connectingsurfaceofanannularchamberandtransferring the liquid inwardly to the nextinner chamber as the'drum rotates.

7. An evaporator as claimed in claim 6, wherein bailles are providedwhere one annular chamber communicates with another for the passage ofvapor.

JAMIE EDWARD BIBBY.

DOES CITED- The following references are of record in the file of thispatent:

the residual liquid discharge means in the evap- 35 UNITED PATENTSPlacek Nov. 21, 1933

